butchering vs manslaughter

butchering

noun
  • The act by which someone or something is butchered; a slaughter or killing. 

manslaughter

noun
  • The unlawful killing of a human, either in negligence or incidentally to the commission of some unlawful act, but without specific malice, or upon a sudden excitement of anger; considered less culpable than murder, but more culpable than justifiable homicide. 

How often have the words butchering and manslaughter occurred in a corpus of books? (source: Google Ngram Viewer )